Detachable aneurysm neck bridge

ABSTRACT

A device for bridging a neck of an aneurysm, comprises a junction region, one or more radially extending array elements secured to the junction region, each array element having an unfolded shape and a delivery shape; and a cover attached to the junction region, and extending over the delivery shape of the array elements, wherein each array element is attached at one end to the junction region and the array elements are constructed and arranged to unfold the cover when assuming their unfolded shape, and wherein the device further comprises a tip, and each array element is attached at another end to the tip, the tip comprising an opening through which a vaso-occlusive device or occlusion fluid may be delivered.

RELATED APPLICATION DATA

This application is a continuation of pending U.S. patent applicationSer. No. 12/768,659, filed Apr. 27, 2010, which is a continuation ofU.S. patent application Ser. No. 12/178,364, filed Jul. 23, 2008, nowissued U.S. Pat. No. 7,713,264, which is a continuation of U.S. patentapplication Ser. No. 10/319,379, filed Dec. 13, 2002, now issued U.S.Pat. No. 7,410,482, which is a continuation-in-part of U.S. patentapplication Ser. No. 09/548,644, filed Apr. 13, 2000, now issued U.S.Pat. No. 7,128,736, which is a continuation of U.S. patent applicationSer. No. 09/148,411 filed Sep. 4, 1998, now abandoned, the disclosuresof which are expressly incorporated by reference herein.

FIELD OF THE INVENTION

The inventions disclosed herein pertain to systems, apparatus, andmethods for treating aneurysms, and more specifically, to systems,apparatus, and methods for bridging a neck of an aneurysm.

BACKGROUND

Various implantable medical devices have been developed for treating anumber of ailments associated with body lumens. In particular, occlusivedevices have been proven useful in filling vascular aneurysms, which areformed due to a weakening in the wall of an artery. Vascular aneurysmsare often the site of internal bleeding and stroke. A variety ofdifferent embolic agents are known to be, at least arguably, suitablefor treatment of vascular aneurysms by filling them to prevent furthervessel wall weakening or rupture. Use of these agents are commonly knownas “artificial vaso-occlusion.”

Over the past few years, advancements in the artificial occlusion ofvessels and aneurysms have included the delivery and implantation ofmetal coils as vaso-occlusive devices. Implantable metal coils that areuseful as artificial occlusion devices in vasculature lumens oraneurysms are herein referred to as “vaso-occlusive coils.”Vaso-occlusive coils are typically constructed of a wire made of a metalor metal alloy wound into a helix. Such vaso-occlusive coils aretypically manufactured to assume a certain shape upon discharge of thedevice from the distal end of the catheter into a treatment site. Avariety of such vaso-occlusive coils are known. For instance, U.S. Pat.No. 4,994,069, issued to Ritchart et al., discloses a flexible,preferably coiled wire for use in small vessel vaso-occlusion. Unlikevaso-occlusive coils used prior to that time, Ritchart et al. disclosesusing a coil that is relatively soft and is delivered to the site usinga pusher within a catheter lumen. Upon discharge from the deliverycatheter, the coil may undertake a number of random or pre-determinedconfigurations useful to fill the site.

Known vaso-occlusive coils may be used for filling relatively smallvessel sites, e.g., 0.5-6.0 mm in diameter. The coils themselves aredescribed as being between 0.254 and 0.762 mm in diameter. The length ofthe wire making up the vaso-occlusive coil is typically 15 to 20 timesthe diameter of the vessel to be occluded. The wire used to make up thecoils may be, for instance, 0.051 to 0.152 mm in diameter. Tungsten,platinum, and gold threads or wires are typically preferred. These coilshave a variety of benefits, including the fact that they are relativelypermanent, they may be easily imaged radiographically, they may belocated at a well defined vessel site, and they can be retrieved, ifnecessary.

In addition to the various types of known space filling mechanisms andgeometries of vaso-occlusive coils, other particularized features ofcoil designs, such as mechanisms for their delivery through cathetersand implanting them in a desired occlusion site, are well know in theart. Examples of known vaso-occlusive coils categorized by theirdelivery mechanisms include pushable coils, mechanically detachablecoils, and electrolytically detachable coils.

One example of a “pushable coil” is disclosed in Ritchart et al.,discussed above. Pushable coils are commonly provided in a cartridge andare pushed or “plunged” from the cartridge into a lumen of a deliverycatheter. A pusher (e.g., a wire or a pressurized fluid) advances thepushable coil through and out of the delivery catheter lumen, into thedesired occlusion site.

Mechanically detachable vaso-occlusive coils are typically integratedwith a pusher rod and are mechanically detached from the distal end ofthat pusher after exiting a delivery catheter. Examples of suchmechanically detachable vaso-occlusive coils are found in U.S. Pat. No.5,261,916 to Engelson and U.S. Pat. No. 5,250,071 to Palermo.

Examples of electrolytically detachable vaso-occlusive coils may befound in U.S. Pat. Nos. 5,122,136 and 5,354,295 issued to Guglielmi etal. In these devices, the vaso-occlusive portion of the assembly isattached to a pusher via a small, electrolytically severable joint. Theelectrolytically severable joint is eroded by the placement of anappropriate voltage on the core wire.

As noted above, aneurysms present a particularly acute medical risk dueto the dangers of potential rupture of the thin vascular wall inherentin such aneurysms. Occlusion of aneurysms by use of vaso-occlusive coilswithout occluding the adjacent artery is a special challenge and is adesirable method of reducing such risk of rupture. Vaso-occlusivedevices may be placed in an aneurysm in a manner described in U.S. Pat.No. 4,739,768 issued to Engelson. In particular, a microcatheter isinitially steered into or adjacent to the entrance of an aneurysm,typically aided by the use of a steerable guidewire. The wire is thenwithdrawn from the microcatheter lumen and replaced by one or morevaso-occlusive coils, which are then advanced through and out of themicrocatheter, and into the aneurysm.

However, after, or perhaps during delivery of a coil into the aneurysm,there is a risk that a portion of the coil might migrate out of theaneurysm entrance zone and into the feeding vessel. The presence of thecoil in that feeding vessel may cause a highly undesirable occlusionthere. Also, there is a risk that the blood flow in the vessel andaneurysm may induce movement of the coil farther out of the aneurysm,resulting in a more developed embolus in the feeding vessel.

One type of aneurysm, commonly known as a “wide neck” aneurysm, is knownto present particular difficulty in the placement and retention ofvaso-occlusive coils, because vaso-occlusive coils lacking substantialsecondary shape strength may be difficult to maintain in position withinan aneurysm no matter how skillfully they are placed. Wide neckaneurysms are herein referred to as aneurysms of vessel walls having aneck or “entrance zone” from the adjacent vessel, wherein the entrancezone has a diameter that either: (1) is at least 80% of the largestdiameter of the aneurysm; or (2) is clinically observed to be too wideeffectively to retain commercially available vaso-occlusive coils thatare deployed using the techniques discussed above.

Certain techniques have been developed in order to deal with thedisadvantages associated with embolic material migration into the parentvessel. One such technique, commonly referred to as flow arrest,involves temporarily occluding the parent vessel proximal of theaneurysm, so that no blood flow occurs through the parent vessel until athrombotic mass has formed in the sac of the aneurysm. While thistechnique helps reduce the tendency of the embolic material to migrateout of the aneurysm sac, a thrombotic mass can still dissolve throughnormal lysis of blood. Also, occluding the parent vessel may not preventall embolic material migration into the parent vessel. Further, incertain cases, it is highly undesirable to occlude the parent vesseleven temporarily. Thus, a flow arrest technique is, at times, noteffective or even not available as a treatment option.

Another approach to occlude a wide neck aneurysm is described in U.S.Pat. No. 6,168,622 (“the '622 patent”), which describes a vaso-occlusivedevice with a secondary shape having a bulbous body portion and ananchor. The bulbous body portion is deployed within the aneurysm whilethe anchor is set just outside of the aneurysm, covering the aneurysm'sneck or entrance zone. As described in the '622 patent, the device maybe integrally formed from a tube—clamped at both ends—of braidedNickel-Titanium (NiTi) wires. The bulbous body functions to occlude theaneurysm, while the anchor covers the entrance zone. In some cases, itmay still be desirable to deploy vaso-occlusive coils with such adevice, but the bulbous body of the vaso-occlusive device may notprovide much space within the aneurysm to allow for insertion anddeployment of coils.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a device forbridging a neck of an aneurysm is described. The device comprises ajunction region, one or more radially extending array elements securedto the junction region, each array element having an unfolded shape anda delivery shape, and a cover attached to the junction region, andextending over the delivery shape of the array elements, wherein eacharray element is attached at one end to the junction region and thearray elements are constructed and arranged to unfold the cover whenassuming their unfolded shape, and wherein the device further comprisesa tip, and each array element is attached at another end to the tip, thetip comprising an opening through which a vaso-occlusive device orocclusion fluid may be delivered.

By way of non-limiting examples, the junction region may furthercomprise a tubular section defining a lumen in communication with thetip opening. The device may further comprise a radio-opaque markercarried on the tip. The cover comprises an elastic material, and may beangiogenic, and/or may comprise an anti-thrombotic agent.

Additionally, the cover may comprise a plurality of loops, where eachloop comprises a fiber having first and second ends attached to thejunction region. The one or more radially extending array elements ofthe device may comprise a wire having a curvilinear shape. Further, theone or more radially extending array elements of the device may comprisea resilient, substantially elastic material, and/or a radio-opaquematerial.

In accordance with another aspect of the present invention, a device forbridging a neck of an aneurysm is described. The device comprises ajunction region, a plurality of radially extending, curvlinear arrayelements secured to the junction region, each array element having anunfolded shape and a delivery shape, and a cover attached to thejunction region, and extending over the delivery shape of the arrayelements, wherein each array element is attached at one end to thejunction region and the array elements are constructed and arranged tounfold the cover when assuming their unfolded shape, and wherein thedevice further comprises a tip, and each array element is attached atanother end to the tip, the tip comprising an opening through which avaso-occlusive device or occlusion fluid may be delivered.

By way of non-limiting examples, the cover may comprise a plurality ofloops, each loop having first and second ends attached to the junctionregion. The radially extending array elements comprise a resilient,substantially elastic material, and /or are constructed of aradio-opaque material.

Other embodiments of the neck bridge in accordance with further aspectsof the invention are also described. By way of non-limiting examples,the neck bridge may optionally be detachably coupled to a distal end ofa delivery member, a core wire, or similar structures via anelectrolytically severable joint or a mechanical joint.

Other aspects, features, and embodiments of the invention are describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of preferred embodimentsof the present invention, in which similar elements are referred to bycommon reference numerals. It should be understood that these drawingsdepict only typical embodiments of the invention and are therefore notto be considered limiting of its scope.

FIG. 1 is a cross sectional plan view of an aneurysm treatment systemincluding a neck bridge comprising an array of elements in accordancewith a preferred embodiment of the invention;

FIG. 2 is a partial cross sectional view of a distal end of the systemof FIG. 1;

FIG. 3 is a partial cross sectional view of a variation of the distalend of the system of FIG. 1, particularly showing a junction region ofthe neck bridge coupling to a distal tip of an inner tubular member;

FIG. 4 is a partial cross sectional view of the distal end of the innertubular member shown in FIG. 3, particularly showing the neck bridgeassuming a delivery shape;

FIG. 5 is a top view of the neck bridge of FIG. 1;

FIG. 6 is a top view of a variation of the neck bridge, particularlyshowing a cover having a plurality of loops;

FIGS. 7A-7C are side views of further variations of the neck bridge;

FIG. 8 is a top view of a still further variation of the neck bridge,particularly showing the array elements having substantially rectilinearshapes;

FIGS. 9A and 9B show another variation of the neck bridge, particularlyshowing the array elements having different unfolded configurations;

FIGS. 10A and 10B show yet another variation of the neck bridge,particularly showing the array elements having upright loop shapes;

FIG. 11 is a side view of a still another variation of the neck bridge,particularly showing the neck bridge having a pair of collars coupled tocontrol wires;

FIG. 12 is a top view of the neck bridge of FIG. 11 in a deployed (i.e.,non-constrained) configuration;

FIG. 13 is a top view of yet another variation of the neck bridge,particularly showing the neck bridge having a braided structure;

FIGS. 14A and 14B show a delivery shape and an unfolded configuration,respectively, of the neck bridge of FIG. 13;

FIGS. 15A and 15B show a variation of the delivery shape and theunfolded configuration, respectively, of the neck bridge of FIG. 13;

FIG. 16 is a further variation of the neck bridge, particularly showingthe junction region of the neck bridge coupled to a wall section of theinner tubular member;

FIG. 17 is a still further variation of the neck bridge, particularlyshowing the junction region of the neck bridge coupled to a core wire bya severable joint;

FIGS. 18A-18E show a procedure for introducing an embodiment of the neckbridge, along with a vaso-occlusive device, into an aneurysm;

FIG. 19A shows a side view of an embodiment of a neck bridge incombination with an “anchor” adapted to be placed within an aneurysm;

FIG. 19B is a top view of the neck bridge of FIG. 19A; and

FIG. 19C shows a placement of the neck bridge depicted in FIG. 19Awithin an aneurysm.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The disclosed invention relates to devices and procedures forstabilizing the position and, in some instances, the structure ofvaso-occlusive devices placed in a target occlusion site, usually ananeurysm. Use of the retaining devices and neck bridges disclosed hereinreduce the potential migration of vaso-occlusive devices (e.g.,helically wound coils) from target occlusion sites, by forming at leasta partial barrier at the entrance zone to the aneurysm, i.e., where theaneurysm meets a feeding vessel.

FIG. 1 shows an aneurysm treatment system 100, which includes ananeurysm neck bridge 106 constructed in accordance with a preferredembodiment. The aneurysm treatment system 100 also includes a tubulardelivery catheter 102, and an inner elongated tubular member 104slidable within the tubular delivery catheter 102. The aneurysm neckbridge 106 is removably coupled to a distal end 107 of the elongatedtubular member 104 via an electrolytically severable joint 122, and isconfigured to be placed within an aneurysm sac or directly across a neck(i.e., in between the tissue defining the neck) of an aneurysm. Thesystem 100 further includes a vaso-occlusive device 108 that isdeliverable via the inner tubular member 104. The vaso-occlusive device108 is coupled to a core wire 110 via another electrolytically severablejoint 130. The severable joints 122 and 130 are of a scale that cannoteasily be seen in FIG. 1 and are depicted in greater clarity in FIG. 2.

Schematically, the electrolytically severable joints 122 and 130 areconfigured to electrically couple to first and second power supplies 112and 114, respectively, which are used to deliver current to severe therespective joints in a well known manner. The severance of the severablejoints 122 and 130 releases the aneurysm neck bridge 106 and thevaso-occlusive device 108, respectively, at the site. Alternatively, asingle power supply may be used to supply current for detachment of thevaso-occlusive device 108 and the aneurysm neck bridge 106.

FIG. 2 is a partial cross section of a distal end of the system 100. Thedistal end 103 of delivery catheter 102 carries a radio-opaque marker116 to assist navigating the distal end 103 through a vasculature. Theinner tubular member 104 also carries a radio-opaque marker 118. Inalternate embodiments, the inner tubular member 104 may have a shapeother than that shown in FIG. 2. For example, the inner tubular member104 may have an angle or a curvilinear shape. Preferably, the innertubular member 104 is malleable or heat settable so that a physician oroperator can create a desired shape at the time the system 100 is used.

A conductor wire 120 is provided for conducting current from the firstpower supply 112 to the electrolytically detachable joint 122. Theaneurysm neck bridge 106 includes a junction region 124, which isdetachably coupled to a distal end 107 of the inner delivery member 104.The junction region 124 may include an opening 128 (shown in FIG. 5),and may have a shape of a tubular member or a ring. The junction region124 preferably fits around the inner tubular member 104 in a loosemanner, and is maintained in position only by the electrolytic joint122. In alternate embodiments, the exterior profile of the junctionregion 124 can vary from the circular shape shown in the illustratedembodiment. Examples of variations in the shape of the junction region124 are shown and described herein.

The severable joint 122 is preferably created by insulating a portion ofthe conductor wire 120. For example, a portion of the conductor wire 120may be insulated with an electrical insulator which is not susceptibleto dissolution via electrolysis in blood or other ionic media, leavingthe un-insulated portion of the conductor wire 120 susceptible toelectrolytic dissolution. The electrical insulator may be the wall ofthe tubular member 104, as shown in FIG. 2, or alternatively, it may bea coating placed over the conductor wire 120. Suitable coatings includeinsulating materials, such as polyfluorocarbons (e.g., Teflon),polyurethane, polyethylene, polypropylene, polyimides, and othersuitable polymeric materials. It will also be apparent that thesacrificial joint 122 is more susceptible to electrolysis than any otherelement of the device located near that joint 122. In use, currentsupplied by the first power supply 112 passes to the electrolyticallyseverable joint 122, typically with the cooperation of an externalreturn electrode pad (not shown) placed on a skin of a patient tocomplete the circuit. Passage of current through the electrolyticallyseverable joint 122 causes the joint 122 to sever, thereby de-couplingthe neck bridge 106 from the tubular member 104.

Further information regarding the construction, placement, and otherphysical details of electrolytically severable joints used may be foundin U.S. Pat. Nos. 5,234,437, 5,250,071, 5,261,916, 5,304,195, 5,312,415,and 5,350,397, the disclosures of which are expressly incorporated byreference herein. It will be appreciated that mechanical joints, andother types of detachable joints known in the art for placing occlusivedevices in aneurysms may alternatively be used to couple the neck bridge106 to the tubular member 104. Examples of such mechanical joints may befound in U.S. Pat. No. 5,234,437, to Sepetka, U.S. Pat. No. 5,250,071 toPalermo, U.S. Pat. No. 5,261,916, to Engelson, U.S. Pat. No. 5,304,195,to Twyford et al., U.S. Pat. No. 5,312,415, to Palermo, and U.S. Pat.No. 5,350,397, to Palermo et al, the disclosures of which are expresslyincorporated herein by reference.

As shown in FIG. 2, because the neck bridge 106 is coupled to thetubular member 104 in a way that does not obstruct the distal opening131 of the tubular member 104, the vaso-occlusive device 108 may bedelivered via the inner tubular member 104. In the illustratedembodiment, the vaso-occlusive device 108 is detachably coupled to adistal end of the core wire 110 by the electrolytically severable joint130, which is formed by insulating a proximal portion of the core wire110 by an insulating layer 125. As noted above, delivery ofvaso-occlusive devices using an electrolytically severable joint is wellknown in the art. Alternatively, the vaso-occlusive device 108 may bedelivered by using a pusher or plunger, the distal advancement of whichwithin the inner tubular member 104 pushes the vaso-occlusive device 108out from the distal end of the inner tubular member 104. Other methodsof delivering the vaso-occlusive device 108 known in the art may also beused.

FIG. 3 shows another variation of the neck bridge 106. Unlike thepreviously shown embodiment, in which the junction region 124 of theneck bridge 106 is configured to fit around the distal end 107 of theinner tubular member 104, the junction region 124 of the neck bridge 106of FIG. 3 is distal to the distal end 107 of the tubular member 104, andis configured to couple to a distal end 107 of the inner tubular member104 via the severable joint 122. In this variation, the cross sectionaldimension of the junction region 124 is substantially the same as thecross sectional dimension of the inner delivery member 104 to form asubstantially continuous outer surface. Vaso-occlusive devices 108exiting the distal end 107 of the tubular member 104 can be delivered toan aneurysm by passing through the opening 128 of the junction region124, as discussed previously. The distal end 107 of the inner tubularmember 104 may further include a Teflon liner or an extension (notshown) coupled to the interior surface of the inner tubular member 104,such that fluid (e.g., an embolic agent) can be delivered through theopening 128 of the junction region 124 without escaping into the gapbetween the tip of the inner tubular member 104 and the junction region124.

The neck bridge 106 includes one or more radially expanding arrayelements or wires 126 attached to the junction region 124, and a cover127 attached to the junction region 124. In alternate embodiments, thecover 127 may also be secured to the array elements 126. In furtheralternate embodiments, the cover 127 may be attached to both the arrayelements 126 and the junction region 124. Upon placement in an aneurysm,the array elements 126 together with the cover 127 spread to the generalshape shown in FIG. 2. In the illustrated embodiment, each of the arrayelements 126 is a wire loop or ribbon rim. The number of array elements126 may vary between embodiments, depending on factors such as the sizeof an aneurysm, the width of the tubular delivery catheter 102, and thethickness of the wire making up the array elements 126. Before the neckbridge 106 is deployed to a target site, the neck bridge 106 resideswithin a lumen 132 of the delivery catheter 102, and it is generallystretched to assume and maintain the shape of the lumen 132 as shown inFIG. 4. The cover 127 is folded into a low profile when positioned inthe lumen 132. When the neck bridge 106 is pushed from the distal end ofthe delivery catheter 102, the array elements 126 assume their so-called“unfolded” shapes or configurations, thereby unfolding the cover 127.

The array elements 126 may be required to undertake relativelysignificant changes in shape during deployment of the neck bridge 106.To undertake such stress, it is usually preferable that the arrayelements 126 be produced of a material such as a super-elastic alloy.Super-elastic or pseudoelastic shape recovery alloys are well known inthis art. For instance, U.S. Pat. Nos. 3,174,851; 3,351,463; and3,753,700 each describe one of the more well known super-elastic alloys,known as Nitinol. These alloys are characterized by their ability to betransformed from an austenitic crystal structure to a stress-inducedmartensitic (SIM) structure at certain temperatures and then to returnelastically to the austenitic shape when the stress is removed. Thesealternating crystal structures provide the alloy with its super-elasticproperties.

The above described alloys are especially suitable because of theircapacity to recover elastically, and almost completely to an unfoldedconfiguration once a bending stress is removed. Typically during use,these alloys suffer little permanent plastic deformation, even atrelatively high strains. This ability allows the neck bridge 106 toundertake substantial bends while residing within the lumen 132 of thetubular delivery catheter 102 and while passing through a vasculature.In spite of this bending, the neck bridge 106 returns to its originalshape, i.e., unfolded configuration, without retaining any substantialpermanent kinks or bends once deployed from the lumen 132.

Of the super-elastic alloys currently available, the preferred materialis 50.6.+−0.2% nickel with most of the remainder being titanium. Up toabout 5% of the alloy may be a member of the iron group of metals,particularly chromium and iron. The alloy is preferred to not containmore than about 500 parts per million of oxygen, carbon, or nitrogen.The transition temperature of this material is not particularlyimportant, but it should be reasonably below the typical temperature ofthe human body so as to allow it to be in its austenitic phase duringuse. The wires or ribbons making up the various array elements 126preferably have a diameter less than about 0.010 inches. Thesesuper-elastic alloys are not always sufficiently visible underfluoroscopy as it is used in the human body. Consequently it may bedesirable to add a radio-opacity covering to the array elements 126.Radio-opaque metals such as gold and platinum are well known.Radio-opaque metals may be added to the array elements 126 by plating orby wrapping the array element 126 in a radio-opaque wire or ribbon, asis known in the art. Alternatively, one or more radio-opaque markers maybe secured to the array elements 126, for example at a perimeter of theneck bridge defined by the array elements 126.

Other metals may also be appropriate for construction of the arrayelements 126. Such metals include stainless steels and other highlyelastic, if not super-elastic, alloys. Polymeric materials which aresomewhat easier to work with in forming a device may also be used forconstruction of the array elements 126. Polymeric materials are somewhateasier to work with in forming a device. Such polymeric materials mayinclude members from the group of polyethylene, polypropylene,polytetraflouroethylene, various Nylons, and the like. Suitable polymersmay also include most biocompatible materials, which may be made intofibers, including thermoplastics, e.g., polyesters such aspolyethyleneterephthalate (PET) especially Dacron; polyamides includingNylons; polyolefins such as polyethylene, polypropylene, polybuylene,their mixtures, alloys, block and random copolymers; polyglycolic acid;polylactic acid; fluoropolymers (polytetrafluoro-ethylene), or even silkor collagen.

FIG. 5 shows a top view of the neck bridge 106. As shown in FIG. 5, thecover 127 is unfolded to have a substantially continuous surface whenthe array elements 126 assume their unfolded configurations. The cover127 may be a fabric, a woven or non-woven mesh, or other sheeting orplanar structure. Although the array elements 126 are each preferably ofa form that retains a large measure of elasticity after having beenbent, the cover 127 may be less elastic. The cover 127 may be made froma variety of materials such as polymers, nylons, and polyester. Thesematerials do not provide substantial strength to the cover 127, so as toallow the device to be readily folded into a low profile and placed intothe delivery catheter lumen 132 without adding unnecessary stiffness.The sole function of the cover 127 is to remain an implantedvaso-occlusive device in an aneurysm. The function of the array elements126 is to maintain the structural integrity of the neck bridge device asit is situated within an aneurysm. Alternatively, the cover 127 may bemade to have a similar elasticity as the array elements 126. Therefore,any of the materials discussed previously with reference to the arrayelements 126 may also be suitable for construction of the cover 127.Other materials suitable for construction of the cover 127 includeDacron (polyethyleneterephthalate), collageneous materials,polyluorocarbons, combinations thereof, and other vascular graftmaterials. Fibrous materials, such as polyglycolic acid, wool, orcotton, may also be used.

FIG. 6 shows a variation of the cover 127, which has a braided ormesh-like structure. In the illustrated embodiment, the neck bridge 106includes six array elements 126 attached to the cover 127. The cover 127includes a plurality of loops 210, each of which formed by securing endsof a fiber to the junction region 124. The loops 210 may overlap oneanother, or alternatively, be inter-woven with each other, to form thecover 127. It should be noted that the shape of the loop 210 is notlimited to that shown in the illustrated embodiment. Furthermore, thecover 127 may have different braided patterns than those shown herein.

In each of the above-described embodiments of the neck bridge, the cover127 may be placed at a top side of the array elements 126 (FIG. 7A), abottom side of the array elements 126 (FIG. 7B), or it may cover bothsides of the array elements 126 (FIG. 7C). In the embodiment shown inFIG. 7C, the neck bridge may further include a disk (not shown) placedbetween the bottom and top surfaces of the cover 127 for reducing theporosity of the neck bridge.

Notably, the shape of the cover 127 is not limited to the circular shapeshown in the previously discussed embodiments. The cover 127 can haveother shapes, such as an elliptical or rectangular shape (FIG. 8).

Generally, as with the embodiments shown in FIGS. 7A and 7C, the cover127 is not required to be directly secured to any of the array elements126. Rather, the array elements 126 exert a bearing and/or frictionalforce on the cover 127 when they assume an unfolded configuration.However, the cover 127 may optionally be secured to the array elements126 at one or more various points. The securing may be accomplishedusing a glue, epoxy, heat bond, or other suitable adhesives, dependingupon the materials from which the respective cover 127 and arrayelements 126 are made. By way of further example, the cover 127 may alsobe secured to the array elements 126 by sewing them together using athread. Securing the cover 127 to the array elements 126 may assist thearray elements 126 in unfolding the cover 127 into a desired shape asthe array elements 126 assume their unfolded configurations.Alternatively, the array elements 126 may be embedded within the cover127, or inter-woven with the cover 127.

It should be noted that the shape of the individual array element is notlimited to the loop shape shown in the previous embodiments, and thatthe array element 126 may have other shapes as well. FIG. 8 shows avariation of the array element 126 that has a substantially rectilinearprofile. As shown in the illustrated embodiment, the array elements mayoptionally have blunted tips to avoid trauma to the arteries in whichthey are placed. The array elements 126 may also have other shapes aswell. In the embodiment of FIG. 8, the cover 127 has a rectangularshape, as previously noted.

The manner in which the array elements fold or bend when positionedwithin the lumen of a tubular delivery member is not limited. By way ofillustration, FIGS. 9A and 9B show another variation of the neck bridge,wherein the array elements 126 are folded in a manner that is differentfrom that shown in FIG. 4. In the embodiment of FIGS. 9A and 9B, each ofthe array elements 126 has an end 211 coupled to a tip 212. The tip 212includes a radio-opaque marker 216. The tip 212 also includes an opening217 through which a vaso-occlusive device or occlusion fluid may bedelivered. The array element 126 has a mid portion that flares outwardwhile maintaining the end 211 of the array element 126 in closeproximity to an axis 214 of the junction region 124. The array elements126 are stretched to the delivery shapes shown in FIG. 9A whenpositioned within the lumen 132 of the delivery catheter 102, and assumethe unfolded configurations shown in FIG. 9B when unconfined outside thedelivery catheter 102. The array elements 126 can also have curvilinearshapes or other unfolded configurations, so long as the array elements126 unfold the cover 127 once deployed outside the lumen 132 of thedelivery catheter 102.

FIGS. 10A and 10B, respectively show side and top views of anothervariation of the neck bridge 106, wherein the array elements 126 haveupright loop shapes. Although the array elements 126 are shown attachingto an interior surface of the junction joint 124, the array elements 126may also be secured to the ends or the side of the junction joint 124.In the illustrated embodiment, the array elements 126 wrap around aperimeter of the cover 127 such that the cover 127 is between the endsof the wires defining the loop shape array elements 126. Alternatively,as shown by the dashed-lines, the cover 127 may also be placed at abottom side of the array elements 126.

The array elements 126 may also be deployed using mechanical methods.FIG. 11 shows another variation of the neck bridge 220 that is deliveredon the exterior of a delivery member 221. This variation includes anumber of radially extending array elements 222 which are joined attheir outer ends. The radially extending array elements 222 are joinedby a cover 224 which also may be scrim-like. The array elements 222 arejoined to a pair of collars 226 that slide on the delivery member 221and are controlled by one or more control wires 228. Each of the controlwires 228 may have a releasable joint 229, desirably an electrolyticallyseverable joint, as discussed previously. During delivery of the neckbridge 220, the array elements 222 lie generally against the deliverymember 221. During deployment, the control wires 228 are axiallymanipulated to extend the radially extending array elements 222 into thedeployed shape depicted in FIG. 12.

In the previously discussed embodiments, the neck bridge includes one ormore array elements attached to the cover. However, the array elementsmay not be required. FIG. 13 shows a variation of the neck bridge whichincludes a junction region 202 and a braided or mesh-like structure 230secured to the junction region 202. The braided structure 230 may carrya radio-opaque marker (not shown), or be plated or coated with aradio-opaque material. The braided structure 230 is preferably made froman elastic material, such as Nitinol. However, any of the materialsdiscussed previously with reference to the array element 216 may also besuitable for construction of the braided structure 230. The advantage ofmaking the braided structure 230 using elastic material is that thebraided structure 230 can assume an unfolded shape without the help ofthe array elements. The braided structure 230 may also be made from aradio-opaque material. In the illustrated embodiment, the braidedstructure 230 includes a number of loops 232, each of which formed bysecuring ends of a fiber to the junction region 202. However, thebraided structure 230 can have other woven or non-woven patterns aswell. FIGS. 14A and 14B show that the braided structure 230 can assume adelivery shape by bending the loops 232 such that the portions of theloops 232 defining the periphery of the braided structure 230 are distalto both ends of the fibers making up the loops 232.

FIGS. 15A and 15B show a variation of the neck bridge of FIG. 13. Asshown in the embodiment, a first end of the fiber making up each of theloops 232 is secured to a first portion 202 a of the junction region202, and a second end of the fiber making up each of the loops 232 issecured to a second portion 202 b of the junction region 202. Whenresiding within the delivery catheter 102, the braided structure 230 isstretched or bent into a delivery shape such as that shown in FIG. 15A.When the neck bridge is deployed outside the delivery catheter 102, thefirst portion 202 a and the second portion 202 b of the junction regionmove closer to each other, and the portion of the loop 232 near themid-section 234 of the loop 232 becomes the periphery of the braidedstructure 230. It should be noted that the manner in which the braidedstructure 230 is folded or deployed should not be limited to theexamples described previously, and that other methods of folding ordeploying the braided structure 230 can also be used.

In all of the previously described embodiments, the junction regionincludes the opening 128 through which a vaso-occlusive device 108 maybe delivered. However, the opening 128 is optional. FIG. 16 shows across sectional view of a variation of the junction region 124 that doesnot have the opening 128. In the illustrated embodiment, the junctionregion 124 is detachably secured to a wall section of the inner tubularmember 104 by an electrolytically severable joint 240. Thevaso-occlusive device 108 may also be delivered via the inner tubularmember 104, as discussed previously.

The neck bridge 126 may be detachably coupled to other structuresinstead of the inner tubular member 104 described previously. FIG. 17shows a cross sectional view of a neck bridge 126 that is detachablycoupled to a core wire 250 by an electrolytically severable joint 252. Aproximal portion of the core wire 250 is insulated by an insulatinglayer 254 to form the severable joint 252. In this case, the deliverycatheter 102 is used to deliver both the neck bridge 106 and thevaso-occlusive device 108.

The method of using the previously described neck bridges will now bediscussed with reference to FIGS. 18A-18E. First, the delivery catheter102 is inserted into the body of a patient. Typically, this would bethrough a femoral artery in the groin.

Other entry sites sometimes chosen are found in the neck and are ingeneral well known by physicians who practice these types of medicalprocedures. The delivery catheter 102, which may be a microcatheter or asheath, may be positioned so that the distal end of the deliverycatheter 102 is appropriately situated, e.g., near the neck of ananeurysm 306 to be treated. (FIG. 18A) The placement of the deliverycatheter 102 may be assisted by the use of guide wire and/or aradio-opaque marker, as are known in the art.

A neck bridge 308, which is representative of any of the embodiments ofthe neck bridge discussed previously, is carried within the deliverycatheter 102 before it is deployed. While positioned within the deliverycatheter 102, the neck bridge 308 is stretched into a delivery shape. Ifthe neck bridge 308 is coupled to the inner tubular member 104, the neckbridge 308 may be deployed by retracting the delivery catheter 102relative to the tubular member 104, or by advancing the tubular member104 relative to the delivery catheter 102. Alternatively, if the neckbridge 308 is coupled to the core wire 250, such as that shown in FIG.17, the neck bridge 308 may be deployed by retracting the deliverycatheter 102 relative to the core wire 250 or by advancing the core wire250 relative to the delivery catheter 102. Once the neck bridge 308 isunconfined outside the delivery catheter 102, it assumes an unfoldedconfiguration. FIG. 18B shows the neck bridge 308 having been deployedand placed within the aneurysm 306.

Next, one or more vaso-occlusive devices 314 may be delivered into theaneurysm using any of the conventional methods. (FIG. 18C) If the neckbridge 308 includes a junction region 316 that has an opening, such asthe opening 128 shown in FIG. 5, the vaso-occlusive device 314 may bedelivered via the inner tubular member 104, through the opening 128 ofthe junction region 316 of the neck bridge 308, and into the aneurysm306. It should be noted that instead of vaso-occlusive devices, otherocclusion substance such as occlusion fluid or occlusion particles mayalso be delivered through the opening of the junction region 316 andinto the aneurysm 306. If the junction region 316 of the neck bridge 308does not have an opening, such as the embodiment shown in FIG. 16 or 17,the vaso-occlusive device 314 may be delivered to the aneurysm 306 alonga path that is exterior to the tubular member 104 or to the core wire250 if one is used. In this case, the neck bridge 308 should be madesufficiently flexible to distend around the vaso-occlusive deliverydevice. Alternatively, the vaso-occlusive device 314 may be deliveredinto the aneurysm 306 by going through an opening in the cover, such asa pre-made opening, or an opening defined by the fibers making up thecover. The vaso-occlusive device 314 may also be delivered into theaneurysm by puncturing the cover of the neck bridge 308.

After a desired number of the vaso-occlusive coils 314 have been placedin the aneurysm 306, the electrolytically severable joint 122 (or joint129, 140, or 252) is then severed, thereby de-coupling the neck bridge308 from the tubular member 104 or from the core wire 250 if one isused. (FIGS. 18D and 18E) The delivery catheter 102 and the innertubular member 104 are then withdrawn, leaving the vaso-occlusive device314 in place within the aneurysm 306. As shown in FIG. 18E, the neckbridge 308 stabilizes the presence of the vaso-occlusive device 314 andprevents the vaso-occlusive coil 314 from being drawn or escaping intothe feed vessel. If desired, a stent or a perfusion balloon mayoptionally be placed in the parent vessel to help seat the neck bridge308 within the aneurysm 306.

It should be noted that the neck bridge may also be placed outside theneck of an aneurysm. FIGS. 19A-19C show another variation of the neckbridge 400 having a junction region 402, a number of radially extendingarray elements 404, and a cover 406. Unlike the previously describedembodiments, the neck bridge 400 also includes a cage 408 made up of aplurality of, e.g., platinum or nickel-titanium coils or wires 409. Aconnector 410 connects the cage 408 to the junction region 402 or to thearray elements 404, and is situated within the neck of the aneurysmafter implantation. The array elements 404 are typically joined to areleasable joint, which may be an electrolytically severable joint asdiscussed previously. As may be seen from FIG. 19B, the cage 408 extendsoutwardly from the general center-line of the device and generallyshould be sized to conform to the size of, and generally to the shapeof, the aneurysm. FIG. 19C shows the general placement of the devicewithin an aneurysm 414. The cage 408, which is within the sac of theaneurysm 414, anchors the cover 406, which is placed outside the neck ofthe aneurysm 414. The method of using the neck bridge 400 is similar tothat described previously with reference to FIGS. 18A-18E.

Many alterations and modifications may be made by those of ordinaryskill in this art, without departing from the spirit and scope of thisinvention. The illustrated embodiments have been shown only for purposesof clarity and the examples should not be taken as limiting theinvention as defined in the following claims, which are intended toinclude all equivalents, whether now or later devised.

1. A device for bridging a neck of an aneurysm, comprising: a junctionregion; one or more radially extending array elements secured to thejunction region, each array element having an unfolded shape and adelivery shape; and a cover attached to the junction region, andextending over the delivery shape of the array elements, wherein eacharray element is attached at one end to the junction region and thearray elements are constructed and arranged to unfold the cover whenassuming their unfolded shape, and wherein the device further comprisesa tip, and each array element is attached at another end to the tip, thetip comprising an opening through which a vaso-occlusive device orocclusion fluid may be delivered.
 2. The device of claim 1, wherein thejunction region comprises a tubular section defining a lumen incommunication with the tip opening.
 3. The device of claim 1, furthercomprising a radio-opaque marker carried on the tip.
 4. The device ofclaim 1, wherein the cover comprises an elastic material.
 5. The deviceof claim 1, wherein the cover is angiogenic.
 6. The device of claim 1,wherein the cover comprises an anti-thrombotic agent.
 7. The device ofclaim 1, wherein the cover comprises a plurality of loops.
 8. The deviceof claim 7, wherein each loop comprising a fiber having first and secondends attached to the junction region.
 9. The device of claim 1, whereinthe one or more radially extending array elements comprise a wire havinga curvilinear shape.
 10. The device of claim 1, wherein the one or moreradially extending array elements comprise a resilient, substantiallyelastic material.
 11. The device of claim 1, wherein the one or moreradially extending array elements comprise a radio-opaque material. 12.A device for bridging a neck of an aneurysm, comprising: a junctionregion; a plurality of radially extending, curvilinear array elementssecured to the junction region, each array element having an unfoldedshape and a delivery shape; and a cover attached to the junction region,and extending over the delivery shape of the array elements, whereineach array element is attached at one end to the junction region and thearray elements are constructed and arranged to unfold the cover whenassuming their unfolded shape, and wherein the device further comprisesa tip, and each array element is attached at another end to the tip, thetip comprising an opening through which a vaso-occlusive device orocclusion fluid may be delivered.
 13. The device of claim 12, whereinthe cover comprises a plurality of loops, each loop having first andsecond ends attached to the junction region.
 14. The device of claim 12,wherein the radially extending array elements comprise a resilient,substantially elastic material.
 15. The device of claim 12, wherein theradially extending array elements are constructed of a radio-opaquematerial.